chore(3p/git): Unvendor git and track patches instead r/2903

This was vendored a long time ago under the expectation that keeping
it in sync with cgit would be easier this way, but it has proven not
to be a big issue.

On the other hand, a vendored copy of git is an annoying maintenance
burden. It is much easier to rebase the single (dottime) patch that we
have.

This removes the vendored copy of git and instead passes the git
source code to cgit via `pkgs.srcOnly`, which includes the applied
patch so that cgit can continue rendering dottime.

Change-Id: If31f62dea7ce688fd1b9050204e9378019775f2b

1 files changed, 0 insertions, 772 deletions

diff --git a/third_party/git/builtin/difftool.c b/third_party/git/builtin/difftool.c
deleted file mode 100644
index 7ac432b88193..000000000000
--- a/third_party/git/builtin/difftool.c
+++ /dev/null
@@ -1,772 +0,0 @@
-/*
- * "git difftool" builtin command
- *
- * This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
- * git-difftool--helper script.
- *
- * This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
- * The GIT_DIFF* variables are exported for use by git-difftool--helper.
- *
- * Any arguments that are unknown to this script are forwarded to 'git diff'.
- *
- * Copyright (C) 2016 Johannes Schindelin
- */
-#define USE_THE_INDEX_COMPATIBILITY_MACROS
-#include "cache.h"
-#include "config.h"
-#include "builtin.h"
-#include "run-command.h"
-#include "exec-cmd.h"
-#include "parse-options.h"
-#include "strvec.h"
-#include "strbuf.h"
-#include "lockfile.h"
-#include "object-store.h"
-#include "dir.h"
-
-static int trust_exit_code;
-
-static const char *const builtin_difftool_usage[] = {
-	N_("git difftool [<options>] [<commit> [<commit>]] [--] [<path>...]"),
-	NULL
-};
-
-static int difftool_config(const char *var, const char *value, void *cb)
-{
-	if (!strcmp(var, "difftool.trustexitcode")) {
-		trust_exit_code = git_config_bool(var, value);
-		return 0;
-	}
-
-	return git_default_config(var, value, cb);
-}
-
-static int print_tool_help(void)
-{
-	const char *argv[] = { "mergetool", "--tool-help=diff", NULL };
-	return run_command_v_opt(argv, RUN_GIT_CMD);
-}
-
-static int parse_index_info(char *p, int *mode1, int *mode2,
-			    struct object_id *oid1, struct object_id *oid2,
-			    char *status)
-{
-	if (*p != ':')
-		return error("expected ':', got '%c'", *p);
-	*mode1 = (int)strtol(p + 1, &p, 8);
-	if (*p != ' ')
-		return error("expected ' ', got '%c'", *p);
-	*mode2 = (int)strtol(p + 1, &p, 8);
-	if (*p != ' ')
-		return error("expected ' ', got '%c'", *p);
-	if (parse_oid_hex(++p, oid1, (const char **)&p))
-		return error("expected object ID, got '%s'", p);
-	if (*p != ' ')
-		return error("expected ' ', got '%c'", *p);
-	if (parse_oid_hex(++p, oid2, (const char **)&p))
-		return error("expected object ID, got '%s'", p);
-	if (*p != ' ')
-		return error("expected ' ', got '%c'", *p);
-	*status = *++p;
-	if (!*status)
-		return error("missing status");
-	if (p[1] && !isdigit(p[1]))
-		return error("unexpected trailer: '%s'", p + 1);
-	return 0;
-}
-
-/*
- * Remove any trailing slash from $workdir
- * before starting to avoid double slashes in symlink targets.
- */
-static void add_path(struct strbuf *buf, size_t base_len, const char *path)
-{
-	strbuf_setlen(buf, base_len);
-	if (buf->len && buf->buf[buf->len - 1] != '/')
-		strbuf_addch(buf, '/');
-	strbuf_addstr(buf, path);
-}
-
-/*
- * Determine whether we can simply reuse the file in the worktree.
- */
-static int use_wt_file(const char *workdir, const char *name,
-		       struct object_id *oid)
-{
-	struct strbuf buf = STRBUF_INIT;
-	struct stat st;
-	int use = 0;
-
-	strbuf_addstr(&buf, workdir);
-	add_path(&buf, buf.len, name);
-
-	if (!lstat(buf.buf, &st) && !S_ISLNK(st.st_mode)) {
-		struct object_id wt_oid;
-		int fd = open(buf.buf, O_RDONLY);
-
-		if (fd >= 0 &&
-		    !index_fd(&the_index, &wt_oid, fd, &st, OBJ_BLOB, name, 0)) {
-			if (is_null_oid(oid)) {
-				oidcpy(oid, &wt_oid);
-				use = 1;
-			} else if (oideq(oid, &wt_oid))
-				use = 1;
-		}
-	}
-
-	strbuf_release(&buf);
-
-	return use;
-}
-
-struct working_tree_entry {
-	struct hashmap_entry entry;
-	char path[FLEX_ARRAY];
-};
-
-static int working_tree_entry_cmp(const void *unused_cmp_data,
-				  const struct hashmap_entry *eptr,
-				  const struct hashmap_entry *entry_or_key,
-				  const void *unused_keydata)
-{
-	const struct working_tree_entry *a, *b;
-
-	a = container_of(eptr, const struct working_tree_entry, entry);
-	b = container_of(entry_or_key, const struct working_tree_entry, entry);
-
-	return strcmp(a->path, b->path);
-}
-
-/*
- * The `left` and `right` entries hold paths for the symlinks hashmap,
- * and a SHA-1 surrounded by brief text for submodules.
- */
-struct pair_entry {
-	struct hashmap_entry entry;
-	char left[PATH_MAX], right[PATH_MAX];
-	const char path[FLEX_ARRAY];
-};
-
-static int pair_cmp(const void *unused_cmp_data,
-		    const struct hashmap_entry *eptr,
-		    const struct hashmap_entry *entry_or_key,
-		    const void *unused_keydata)
-{
-	const struct pair_entry *a, *b;
-
-	a = container_of(eptr, const struct pair_entry, entry);
-	b = container_of(entry_or_key, const struct pair_entry, entry);
-
-	return strcmp(a->path, b->path);
-}
-
-static void add_left_or_right(struct hashmap *map, const char *path,
-			      const char *content, int is_right)
-{
-	struct pair_entry *e, *existing;
-
-	FLEX_ALLOC_STR(e, path, path);
-	hashmap_entry_init(&e->entry, strhash(path));
-	existing = hashmap_get_entry(map, e, entry, NULL);
-	if (existing) {
-		free(e);
-		e = existing;
-	} else {
-		e->left[0] = e->right[0] = '\0';
-		hashmap_add(map, &e->entry);
-	}
-	strlcpy(is_right ? e->right : e->left, content, PATH_MAX);
-}
-
-struct path_entry {
-	struct hashmap_entry entry;
-	char path[FLEX_ARRAY];
-};
-
-static int path_entry_cmp(const void *unused_cmp_data,
-			  const struct hashmap_entry *eptr,
-			  const struct hashmap_entry *entry_or_key,
-			  const void *key)
-{
-	const struct path_entry *a, *b;
-
-	a = container_of(eptr, const struct path_entry, entry);
-	b = container_of(entry_or_key, const struct path_entry, entry);
-
-	return strcmp(a->path, key ? key : b->path);
-}
-
-static void changed_files(struct hashmap *result, const char *index_path,
-			  const char *workdir)
-{
-	struct child_process update_index = CHILD_PROCESS_INIT;
-	struct child_process diff_files = CHILD_PROCESS_INIT;
-	struct strbuf index_env = STRBUF_INIT, buf = STRBUF_INIT;
-	const char *git_dir = absolute_path(get_git_dir()), *env[] = {
-		NULL, NULL
-	};
-	FILE *fp;
-
-	strbuf_addf(&index_env, "GIT_INDEX_FILE=%s", index_path);
-	env[0] = index_env.buf;
-
-	strvec_pushl(&update_index.args,
-		     "--git-dir", git_dir, "--work-tree", workdir,
-		     "update-index", "--really-refresh", "-q",
-		     "--unmerged", NULL);
-	update_index.no_stdin = 1;
-	update_index.no_stdout = 1;
-	update_index.no_stderr = 1;
-	update_index.git_cmd = 1;
-	update_index.use_shell = 0;
-	update_index.clean_on_exit = 1;
-	update_index.dir = workdir;
-	update_index.env = env;
-	/* Ignore any errors of update-index */
-	run_command(&update_index);
-
-	strvec_pushl(&diff_files.args,
-		     "--git-dir", git_dir, "--work-tree", workdir,
-		     "diff-files", "--name-only", "-z", NULL);
-	diff_files.no_stdin = 1;
-	diff_files.git_cmd = 1;
-	diff_files.use_shell = 0;
-	diff_files.clean_on_exit = 1;
-	diff_files.out = -1;
-	diff_files.dir = workdir;
-	diff_files.env = env;
-	if (start_command(&diff_files))
-		die("could not obtain raw diff");
-	fp = xfdopen(diff_files.out, "r");
-	while (!strbuf_getline_nul(&buf, fp)) {
-		struct path_entry *entry;
-		FLEX_ALLOC_STR(entry, path, buf.buf);
-		hashmap_entry_init(&entry->entry, strhash(buf.buf));
-		hashmap_add(result, &entry->entry);
-	}
-	fclose(fp);
-	if (finish_command(&diff_files))
-		die("diff-files did not exit properly");
-	strbuf_release(&index_env);
-	strbuf_release(&buf);
-}
-
-static NORETURN void exit_cleanup(const char *tmpdir, int exit_code)
-{
-	struct strbuf buf = STRBUF_INIT;
-	strbuf_addstr(&buf, tmpdir);
-	remove_dir_recursively(&buf, 0);
-	if (exit_code)
-		warning(_("failed: %d"), exit_code);
-	exit(exit_code);
-}
-
-static int ensure_leading_directories(char *path)
-{
-	switch (safe_create_leading_directories(path)) {
-		case SCLD_OK:
-		case SCLD_EXISTS:
-			return 0;
-		default:
-			return error(_("could not create leading directories "
-				       "of '%s'"), path);
-	}
-}
-
-/*
- * Unconditional writing of a plain regular file is what
- * "git difftool --dir-diff" wants to do for symlinks.  We are preparing two
- * temporary directories to be fed to a Git-unaware tool that knows how to
- * show a diff of two directories (e.g. "diff -r A B").
- *
- * Because the tool is Git-unaware, if a symbolic link appears in either of
- * these temporary directories, it will try to dereference and show the
- * difference of the target of the symbolic link, which is not what we want,
- * as the goal of the dir-diff mode is to produce an output that is logically
- * equivalent to what "git diff" produces.
- *
- * Most importantly, we want to get textual comparison of the result of the
- * readlink(2).  get_symlink() provides that---it returns the contents of
- * the symlink that gets written to a regular file to force the external tool
- * to compare the readlink(2) result as text, even on a filesystem that is
- * capable of doing a symbolic link.
- */
-static char *get_symlink(const struct object_id *oid, const char *path)
-{
-	char *data;
-	if (is_null_oid(oid)) {
-		/* The symlink is unknown to Git so read from the filesystem */
-		struct strbuf link = STRBUF_INIT;
-		if (has_symlinks) {
-			if (strbuf_readlink(&link, path, strlen(path)))
-				die(_("could not read symlink %s"), path);
-		} else if (strbuf_read_file(&link, path, 128))
-			die(_("could not read symlink file %s"), path);
-
-		data = strbuf_detach(&link, NULL);
-	} else {
-		enum object_type type;
-		unsigned long size;
-		data = read_object_file(oid, &type, &size);
-		if (!data)
-			die(_("could not read object %s for symlink %s"),
-				oid_to_hex(oid), path);
-	}
-
-	return data;
-}
-
-static int checkout_path(unsigned mode, struct object_id *oid,
-			 const char *path, const struct checkout *state)
-{
-	struct cache_entry *ce;
-	int ret;
-
-	ce = make_transient_cache_entry(mode, oid, path, 0);
-	ret = checkout_entry(ce, state, NULL, NULL);
-
-	discard_cache_entry(ce);
-	return ret;
-}
-
-static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
-			int argc, const char **argv)
-{
-	char tmpdir[PATH_MAX];
-	struct strbuf info = STRBUF_INIT, lpath = STRBUF_INIT;
-	struct strbuf rpath = STRBUF_INIT, buf = STRBUF_INIT;
-	struct strbuf ldir = STRBUF_INIT, rdir = STRBUF_INIT;
-	struct strbuf wtdir = STRBUF_INIT;
-	char *lbase_dir, *rbase_dir;
-	size_t ldir_len, rdir_len, wtdir_len;
-	const char *workdir, *tmp;
-	int ret = 0, i;
-	FILE *fp;
-	struct hashmap working_tree_dups, submodules, symlinks2;
-	struct hashmap_iter iter;
-	struct pair_entry *entry;
-	struct index_state wtindex;
-	struct checkout lstate, rstate;
-	int rc, flags = RUN_GIT_CMD, err = 0;
-	struct child_process child = CHILD_PROCESS_INIT;
-	const char *helper_argv[] = { "difftool--helper", NULL, NULL, NULL };
-	struct hashmap wt_modified, tmp_modified;
-	int indices_loaded = 0;
-
-	workdir = get_git_work_tree();
-
-	/* Setup temp directories */
-	tmp = getenv("TMPDIR");
-	xsnprintf(tmpdir, sizeof(tmpdir), "%s/git-difftool.XXXXXX", tmp ? tmp : "/tmp");
-	if (!mkdtemp(tmpdir))
-		return error("could not create '%s'", tmpdir);
-	strbuf_addf(&ldir, "%s/left/", tmpdir);
-	strbuf_addf(&rdir, "%s/right/", tmpdir);
-	strbuf_addstr(&wtdir, workdir);
-	if (!wtdir.len || !is_dir_sep(wtdir.buf[wtdir.len - 1]))
-		strbuf_addch(&wtdir, '/');
-	mkdir(ldir.buf, 0700);
-	mkdir(rdir.buf, 0700);
-
-	memset(&wtindex, 0, sizeof(wtindex));
-
-	memset(&lstate, 0, sizeof(lstate));
-	lstate.base_dir = lbase_dir = xstrdup(ldir.buf);
-	lstate.base_dir_len = ldir.len;
-	lstate.force = 1;
-	memset(&rstate, 0, sizeof(rstate));
-	rstate.base_dir = rbase_dir = xstrdup(rdir.buf);
-	rstate.base_dir_len = rdir.len;
-	rstate.force = 1;
-
-	ldir_len = ldir.len;
-	rdir_len = rdir.len;
-	wtdir_len = wtdir.len;
-
-	hashmap_init(&working_tree_dups, working_tree_entry_cmp, NULL, 0);
-	hashmap_init(&submodules, pair_cmp, NULL, 0);
-	hashmap_init(&symlinks2, pair_cmp, NULL, 0);
-
-	child.no_stdin = 1;
-	child.git_cmd = 1;
-	child.use_shell = 0;
-	child.clean_on_exit = 1;
-	child.dir = prefix;
-	child.out = -1;
-	strvec_pushl(&child.args, "diff", "--raw", "--no-abbrev", "-z",
-		     NULL);
-	for (i = 0; i < argc; i++)
-		strvec_push(&child.args, argv[i]);
-	if (start_command(&child))
-		die("could not obtain raw diff");
-	fp = xfdopen(child.out, "r");
-
-	/* Build index info for left and right sides of the diff */
-	i = 0;
-	while (!strbuf_getline_nul(&info, fp)) {
-		int lmode, rmode;
-		struct object_id loid, roid;
-		char status;
-		const char *src_path, *dst_path;
-
-		if (starts_with(info.buf, "::"))
-			die(N_("combined diff formats('-c' and '--cc') are "
-			       "not supported in\n"
-			       "directory diff mode('-d' and '--dir-diff')."));
-
-		if (parse_index_info(info.buf, &lmode, &rmode, &loid, &roid,
-				     &status))
-			break;
-		if (strbuf_getline_nul(&lpath, fp))
-			break;
-		src_path = lpath.buf;
-
-		i++;
-		if (status != 'C' && status != 'R') {
-			dst_path = src_path;
-		} else {
-			if (strbuf_getline_nul(&rpath, fp))
-				break;
-			dst_path = rpath.buf;
-		}
-
-		if (S_ISGITLINK(lmode) || S_ISGITLINK(rmode)) {
-			strbuf_reset(&buf);
-			strbuf_addf(&buf, "Subproject commit %s",
-				    oid_to_hex(&loid));
-			add_left_or_right(&submodules, src_path, buf.buf, 0);
-			strbuf_reset(&buf);
-			strbuf_addf(&buf, "Subproject commit %s",
-				    oid_to_hex(&roid));
-			if (oideq(&loid, &roid))
-				strbuf_addstr(&buf, "-dirty");
-			add_left_or_right(&submodules, dst_path, buf.buf, 1);
-			continue;
-		}
-
-		if (S_ISLNK(lmode)) {
-			char *content = get_symlink(&loid, src_path);
-			add_left_or_right(&symlinks2, src_path, content, 0);
-			free(content);
-		}
-
-		if (S_ISLNK(rmode)) {
-			char *content = get_symlink(&roid, dst_path);
-			add_left_or_right(&symlinks2, dst_path, content, 1);
-			free(content);
-		}
-
-		if (lmode && status != 'C') {
-			if (checkout_path(lmode, &loid, src_path, &lstate)) {
-				ret = error("could not write '%s'", src_path);
-				goto finish;
-			}
-		}
-
-		if (rmode && !S_ISLNK(rmode)) {
-			struct working_tree_entry *entry;
-
-			/* Avoid duplicate working_tree entries */
-			FLEX_ALLOC_STR(entry, path, dst_path);
-			hashmap_entry_init(&entry->entry, strhash(dst_path));
-			if (hashmap_get(&working_tree_dups, &entry->entry,
-					NULL)) {
-				free(entry);
-				continue;
-			}
-			hashmap_add(&working_tree_dups, &entry->entry);
-
-			if (!use_wt_file(workdir, dst_path, &roid)) {
-				if (checkout_path(rmode, &roid, dst_path,
-						  &rstate)) {
-					ret = error("could not write '%s'",
-						    dst_path);
-					goto finish;
-				}
-			} else if (!is_null_oid(&roid)) {
-				/*
-				 * Changes in the working tree need special
-				 * treatment since they are not part of the
-				 * index.
-				 */
-				struct cache_entry *ce2 =
-					make_cache_entry(&wtindex, rmode, &roid,
-							 dst_path, 0, 0);
-
-				add_index_entry(&wtindex, ce2,
-						ADD_CACHE_JUST_APPEND);
-
-				add_path(&rdir, rdir_len, dst_path);
-				if (ensure_leading_directories(rdir.buf)) {
-					ret = error("could not create "
-						    "directory for '%s'",
-						    dst_path);
-					goto finish;
-				}
-				add_path(&wtdir, wtdir_len, dst_path);
-				if (symlinks) {
-					if (symlink(wtdir.buf, rdir.buf)) {
-						ret = error_errno("could not symlink '%s' to '%s'", wtdir.buf, rdir.buf);
-						goto finish;
-					}
-				} else {
-					struct stat st;
-					if (stat(wtdir.buf, &st))
-						st.st_mode = 0644;
-					if (copy_file(rdir.buf, wtdir.buf,
-						      st.st_mode)) {
-						ret = error("could not copy '%s' to '%s'", wtdir.buf, rdir.buf);
-						goto finish;
-					}
-				}
-			}
-		}
-	}
-
-	fclose(fp);
-	fp = NULL;
-	if (finish_command(&child)) {
-		ret = error("error occurred running diff --raw");
-		goto finish;
-	}
-
-	if (!i)
-		goto finish;
-
-	/*
-	 * Changes to submodules require special treatment.This loop writes a
-	 * temporary file to both the left and right directories to show the
-	 * change in the recorded SHA1 for the submodule.
-	 */
-	hashmap_for_each_entry(&submodules, &iter, entry,
-				entry /* member name */) {
-		if (*entry->left) {
-			add_path(&ldir, ldir_len, entry->path);
-			ensure_leading_directories(ldir.buf);
-			write_file(ldir.buf, "%s", entry->left);
-		}
-		if (*entry->right) {
-			add_path(&rdir, rdir_len, entry->path);
-			ensure_leading_directories(rdir.buf);
-			write_file(rdir.buf, "%s", entry->right);
-		}
-	}
-
-	/*
-	 * Symbolic links require special treatment.The standard "git diff"
-	 * shows only the link itself, not the contents of the link target.
-	 * This loop replicates that behavior.
-	 */
-	hashmap_for_each_entry(&symlinks2, &iter, entry,
-				entry /* member name */) {
-		if (*entry->left) {
-			add_path(&ldir, ldir_len, entry->path);
-			ensure_leading_directories(ldir.buf);
-			write_file(ldir.buf, "%s", entry->left);
-		}
-		if (*entry->right) {
-			add_path(&rdir, rdir_len, entry->path);
-			ensure_leading_directories(rdir.buf);
-			write_file(rdir.buf, "%s", entry->right);
-		}
-	}
-
-	strbuf_release(&buf);
-
-	strbuf_setlen(&ldir, ldir_len);
-	helper_argv[1] = ldir.buf;
-	strbuf_setlen(&rdir, rdir_len);
-	helper_argv[2] = rdir.buf;
-
-	if (extcmd) {
-		helper_argv[0] = extcmd;
-		flags = 0;
-	} else
-		setenv("GIT_DIFFTOOL_DIRDIFF", "true", 1);
-	rc = run_command_v_opt(helper_argv, flags);
-
-	/*
-	 * If the diff includes working copy files and those
-	 * files were modified during the diff, then the changes
-	 * should be copied back to the working tree.
-	 * Do not copy back files when symlinks are used and the
-	 * external tool did not replace the original link with a file.
-	 *
-	 * These hashes are loaded lazily since they aren't needed
-	 * in the common case of --symlinks and the difftool updating
-	 * files through the symlink.
-	 */
-	hashmap_init(&wt_modified, path_entry_cmp, NULL, wtindex.cache_nr);
-	hashmap_init(&tmp_modified, path_entry_cmp, NULL, wtindex.cache_nr);
-
-	for (i = 0; i < wtindex.cache_nr; i++) {
-		struct hashmap_entry dummy;
-		const char *name = wtindex.cache[i]->name;
-		struct stat st;
-
-		add_path(&rdir, rdir_len, name);
-		if (lstat(rdir.buf, &st))
-			continue;
-
-		if ((symlinks && S_ISLNK(st.st_mode)) || !S_ISREG(st.st_mode))
-			continue;
-
-		if (!indices_loaded) {
-			struct lock_file lock = LOCK_INIT;
-			strbuf_reset(&buf);
-			strbuf_addf(&buf, "%s/wtindex", tmpdir);
-			if (hold_lock_file_for_update(&lock, buf.buf, 0) < 0 ||
-			    write_locked_index(&wtindex, &lock, COMMIT_LOCK)) {
-				ret = error("could not write %s", buf.buf);
-				goto finish;
-			}
-			changed_files(&wt_modified, buf.buf, workdir);
-			strbuf_setlen(&rdir, rdir_len);
-			changed_files(&tmp_modified, buf.buf, rdir.buf);
-			add_path(&rdir, rdir_len, name);
-			indices_loaded = 1;
-		}
-
-		hashmap_entry_init(&dummy, strhash(name));
-		if (hashmap_get(&tmp_modified, &dummy, name)) {
-			add_path(&wtdir, wtdir_len, name);
-			if (hashmap_get(&wt_modified, &dummy, name)) {
-				warning(_("both files modified: '%s' and '%s'."),
-					wtdir.buf, rdir.buf);
-				warning(_("working tree file has been left."));
-				warning("%s", "");
-				err = 1;
-			} else if (unlink(wtdir.buf) ||
-				   copy_file(wtdir.buf, rdir.buf, st.st_mode))
-				warning_errno(_("could not copy '%s' to '%s'"),
-					      rdir.buf, wtdir.buf);
-		}
-	}
-
-	if (err) {
-		warning(_("temporary files exist in '%s'."), tmpdir);
-		warning(_("you may want to cleanup or recover these."));
-		exit(1);
-	} else
-		exit_cleanup(tmpdir, rc);
-
-finish:
-	if (fp)
-		fclose(fp);
-
-	free(lbase_dir);
-	free(rbase_dir);
-	strbuf_release(&ldir);
-	strbuf_release(&rdir);
-	strbuf_release(&wtdir);
-	strbuf_release(&buf);
-
-	return ret;
-}
-
-static int run_file_diff(int prompt, const char *prefix,
-			 int argc, const char **argv)
-{
-	struct strvec args = STRVEC_INIT;
-	const char *env[] = {
-		"GIT_PAGER=", "GIT_EXTERNAL_DIFF=git-difftool--helper", NULL,
-		NULL
-	};
-	int ret = 0, i;
-
-	if (prompt > 0)
-		env[2] = "GIT_DIFFTOOL_PROMPT=true";
-	else if (!prompt)
-		env[2] = "GIT_DIFFTOOL_NO_PROMPT=true";
-
-
-	strvec_push(&args, "diff");
-	for (i = 0; i < argc; i++)
-		strvec_push(&args, argv[i]);
-	ret = run_command_v_opt_cd_env(args.v, RUN_GIT_CMD, prefix, env);
-	exit(ret);
-}
-
-int cmd_difftool(int argc, const char **argv, const char *prefix)
-{
-	int use_gui_tool = 0, dir_diff = 0, prompt = -1, symlinks = 0,
-	    tool_help = 0, no_index = 0;
-	static char *difftool_cmd = NULL, *extcmd = NULL;
-	struct option builtin_difftool_options[] = {
-		OPT_BOOL('g', "gui", &use_gui_tool,
-			 N_("use `diff.guitool` instead of `diff.tool`")),
-		OPT_BOOL('d', "dir-diff", &dir_diff,
-			 N_("perform a full-directory diff")),
-		OPT_SET_INT_F('y', "no-prompt", &prompt,
-			N_("do not prompt before launching a diff tool"),
-			0, PARSE_OPT_NONEG),
-		OPT_SET_INT_F(0, "prompt", &prompt, NULL,
-			1, PARSE_OPT_NONEG | PARSE_OPT_HIDDEN),
-		OPT_BOOL(0, "symlinks", &symlinks,
-			 N_("use symlinks in dir-diff mode")),
-		OPT_STRING('t', "tool", &difftool_cmd, N_("tool"),
-			   N_("use the specified diff tool")),
-		OPT_BOOL(0, "tool-help", &tool_help,
-			 N_("print a list of diff tools that may be used with "
-			    "`--tool`")),
-		OPT_BOOL(0, "trust-exit-code", &trust_exit_code,
-			 N_("make 'git-difftool' exit when an invoked diff "
-			    "tool returns a non - zero exit code")),
-		OPT_STRING('x', "extcmd", &extcmd, N_("command"),
-			   N_("specify a custom command for viewing diffs")),
-		OPT_ARGUMENT("no-index", &no_index, N_("passed to `diff`")),
-		OPT_END()
-	};
-
-	git_config(difftool_config, NULL);
-	symlinks = has_symlinks;
-
-	argc = parse_options(argc, argv, prefix, builtin_difftool_options,
-			     builtin_difftool_usage, PARSE_OPT_KEEP_UNKNOWN |
-			     PARSE_OPT_KEEP_DASHDASH);
-
-	if (tool_help)
-		return print_tool_help();
-
-	if (!no_index && !startup_info->have_repository)
-		die(_("difftool requires worktree or --no-index"));
-
-	if (!no_index){
-		setup_work_tree();
-		setenv(GIT_DIR_ENVIRONMENT, absolute_path(get_git_dir()), 1);
-		setenv(GIT_WORK_TREE_ENVIRONMENT, absolute_path(get_git_work_tree()), 1);
-	} else if (dir_diff)
-		die(_("--dir-diff is incompatible with --no-index"));
-
-	if (use_gui_tool + !!difftool_cmd + !!extcmd > 1)
-		die(_("--gui, --tool and --extcmd are mutually exclusive"));
-
-	if (use_gui_tool)
-		setenv("GIT_MERGETOOL_GUI", "true", 1);
-	else if (difftool_cmd) {
-		if (*difftool_cmd)
-			setenv("GIT_DIFF_TOOL", difftool_cmd, 1);
-		else
-			die(_("no <tool> given for --tool=<tool>"));
-	}
-
-	if (extcmd) {
-		if (*extcmd)
-			setenv("GIT_DIFFTOOL_EXTCMD", extcmd, 1);
-		else
-			die(_("no <cmd> given for --extcmd=<cmd>"));
-	}
-
-	setenv("GIT_DIFFTOOL_TRUST_EXIT_CODE",
-	       trust_exit_code ? "true" : "false", 1);
-
-	/*
-	 * In directory diff mode, 'git-difftool--helper' is called once
-	 * to compare the a / b directories. In file diff mode, 'git diff'
-	 * will invoke a separate instance of 'git-difftool--helper' for
-	 * each file that changed.
-	 */
-	if (dir_diff)
-		return run_dir_diff(extcmd, symlinks, prefix, argc, argv);
-	return run_file_diff(prompt, prefix, argc, argv);
-}